FC 59 - Digital Transfer

This function code selects one of two digital inputs, depending on a transfer switch signal. The state of the transfer switch <S3> is determined externally, either by automatic control or by an operator.

 

 

Outputs:

Blk

Type

Description

N

B

Value of selected input

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

0

I

Note 1

Block address of first input

S2

N

0

I

Note 1

Block address of second input

S3

N

0

I

Note 1

Block address of track switch signal:

0 = <S1>

1 = <S2>

 

NOTES:

1. Maximum values are: 9,998 for the BRC-100, IMMFP11/12 and 31,998 for the HAC

 

 

59.1 Applications

 

Function code 59 can control equipment based on the status of other equipment or digital inputs. Figure 59-1 illustrates a safety feature.

 

 

 

The controlled reserve pump must activate if less than three of four primary pumps are functioning. The function code 59 block controls the status of the reserve pump.

 

<S1> = 1 (on), and <S2> = 0 (off)

 

The transfer switch is the output of a qualified OR block. If less than three pumps are operating, then the output of the qualified OR block will be at zero. That output is the <S3> input to the digital transfer block. A zero input for <S3> causes <S1> to be the output from the block. When <S1> equals one (on), the pump activates. When three or more of the pumps are operational, the pump will be turned off.